Spotify Streamable MCP Server

/** * Roots utilities for server→client requests. * * ⚠️ NODE.JS ONLY - These utilities require SDK bidirectional support * (server.request()) which is not available in the Cloudflare Workers runtime. * The Workers dispatcher does not support server→client requests. * * Per MCP spec (review finding #2): * - Roots is a CLIENT capability * - Servers send roots/list requests TO clients * - Clients respond with filesystem locations they have access to * - This enables file-based tools to know allowed paths */ import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'; import { logger } from './logger.js'; /** * A root directory or file that the client has access to. * Per spec: URI MUST start with "file://" */ export interface Root { /** The URI identifying the root. MUST start with "file://" */ uri: string; /** Optional display name for the root */ name?: string; /** Extension metadata */ _meta?: Record<string, unknown>; } /** * Result from roots/list request. */ export interface ListRootsResult { roots: Root[]; } /** * Request the list of roots from the client. * * @param server - The MCP server instance * @returns Array of Root objects representing accessible filesystem locations * @throws Error if client doesn't support roots capability * * @example * ```typescript * const roots = await requestRoots(server); * for (const root of roots) { * console.log(`Root: ${root.name ?? root.uri}`); * } * ``` */ export async function requestRoots(server: McpServer): Promise<Root[]> { logger.debug('roots', { message: 'Requesting roots from client', }); try { // biome-ignore lint/suspicious/noExplicitAny: accessing private SDK property const lowLevel = (server as any).server ?? server; if (!lowLevel.request) { throw new Error('Roots not supported: Server does not support client requests'); } // Check client capability before requesting const clientCapabilities = lowLevel.getClientCapabilities?.() ?? {}; if (!clientCapabilities.roots) { throw new Error( 'Client does not support roots capability. ' + 'Client must declare "roots" capability to list filesystem roots.', ); } const response = await lowLevel.request( { method: 'roots/list' }, // Schema for validation (simplified) { parse: (r: unknown) => r as ListRootsResult }, ); logger.info('roots', { message: 'Received roots from client', rootCount: response.roots.length, }); return response.roots; } catch (error) { logger.error('roots', { message: 'Roots request failed', error: (error as Error).message, }); // Check if client doesn't support roots // biome-ignore lint/suspicious/noExplicitAny: checking JSON-RPC error code if ((error as any).code === -32601) { throw new Error( 'Roots not supported by client. Client must declare "roots" capability.', ); } throw error; } } /** * Check if the client supports roots. * * @param server - The MCP server instance * @returns true if client declared roots capability */ export function clientSupportsRoots(server: McpServer): boolean { try { // biome-ignore lint/suspicious/noExplicitAny: accessing private SDK property const lowLevel = (server as any).server ?? server; const clientCapabilities = lowLevel.getClientCapabilities?.() ?? {}; return Boolean(clientCapabilities.roots); } catch { return false; } } /** * Check if the client supports roots list change notifications. * * @param server - The MCP server instance * @returns true if client declared roots.listChanged capability */ export function clientSupportsRootsListChanged(server: McpServer): boolean { try { // biome-ignore lint/suspicious/noExplicitAny: accessing private SDK property const lowLevel = (server as any).server ?? server; const clientCapabilities = lowLevel.getClientCapabilities?.() ?? {}; return Boolean(clientCapabilities.roots?.listChanged); } catch { return false; } }